audioguru Posted December 8, 2006 Report Share Posted December 8, 2006 total Z seen by the MIC (Zmic)= 10K//11.2K= 5.3KCorrect.C1 (=330n) and Zmic are a high pass filter, its cut off freq (Fo)Fo= 1/(2 pi C1 Zmic)= 91 HzNo. The mic impedance is about 5k and it is in parallel with its 10k load/powering resistor so it has an effective series resistance of 3.3k. The 3.3k, the 330nF coupling capacitor and the 11.2k load resistance are all in series so the cutoff frequency is 1/(2 pi C1 [3.3k + 11.2K])= 33Hz.Fo = 64 Hz, so this filter cuts all freqs less than 64Hz including mains hum.No. This is a very simple filter. At the cutoff frequency the response is down -3dB which is a small amount. If the cutoff frequency is 500Hz then 50Hz would be reduced but not eliminated. Quote Link to comment Share on other sites More sharing options...
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